Adding additional parameter to loan product

Added a new parameter to loan product which ties the amount approved to savings account balance for the client..

If a product has a factor of 2.5 and client has a savings balance of 1000 then client can only borrow up to 2500. An exception is thrown at loan approval if the principal is above the limit .

1. I want to retrieve the savings account balance for the client in LoansApiResource.java . I have tried fetching it as part of association parameter but im having difficulty..Is there an alternative way to achieve this

2.Which of the three methods should i use in my POST ..

3. Is my implementation for retrieving lending factor value correct..

4.Should i retrieve principal from disbursementData in or from LoanAccountData.basicLoanDetails in LoanReadPlatformService,java